-The team-based nature of the game
-SMART system
-the side objectives, adds depth to the game
-how well done the class system seems to be
-the customization (not that original but still great)
-A body type system on top of the class system
-you get to pick your side in the singleplayer,
-both sides have a valid reason to fight instead of some basic "good guy vs bad guy" crap
-blending of single player and multiplayer,
-Low bullet damage and lack of 1 hit kill weapons
-no sniper class
There are some things I don't like though, like the cartoony art style (just personal taste, not really a problem), but mostly the scale.
I don't buy games with less than 24 players online, but I will probably make and exception for BRINK. If I could change something about this game I would make it have 24 or 32 players online, I would say for 64 player online but that would be unreasonable (with bigger maps and dedicated servers on consoles to support it). Also organized squad systems with squad leaders with special abilities like designating one kind of objective as the current priority (say the enemy has all the command posts, setting command posts as priority targets would tell your squad to focus on getting command posts), and waypoints on the map to tell your squad where to attack from. Things like orders and waypoints should yield exp bonuses to act as incentives. Also, 1 team leader position on each side whose job it is coordinate with squad leaders, and give orders to his entire team, and also has similar abilities as the squad leader, but for his entire team and not just for one squad (waypoints and priority orders from team-leader would override those from a squad leader). With much bigger maps, having to spawn all the way back in base could be annoying, so maybe squad members should be able to spawn on their squad leader (won't be a problem if squads are small and only hold 4 players). Or maybe there could be mobile spawn points, vehicles that act as spawn points like an APC. Maybe some kind of secondary objective may act as spawn points for whatever team captures it, and it could be the squad leader's side-objective (on top of his class-designated side objective).
Just kind of throwing out ideas as I'm typing, but mainly I just wish BRINK had had scale, bigger maps, more players.
The reason I will probably buy this game despite the small scale was that I got burned by another team/objective-based shooter: Killzone3, there were nice additions and improvements, but overall the game got dumbed down from its predecessor to appeal to the casual crowd, there is lots of imbalance, on top of that it got rushed and many problems from the beta still aren't fixed after release (it got released like a week after the beta). I'm going to be on the SOCOM4 multiplayer beta in a bit over a week fron now, I usually don't like third person shooters, but the developers made my favorite tacticial/team/objective-based shooter of all time (MAG), the game will have 32 player online (not 256 player but still awesome), destructible environments, dedicated servers, custom games, clan battles, focus on teamwork, and other good stuff. Its between SOCOM4 and BRINK for me right now (with only 2 options I can't really be so picky), but Brink looks far more innovative, and regular modern-day settings of SOCOM4 look boring... I'm kind of getting off topic.
Is there anything you wish you could change about BRINK? If so, what would you change?